1. Field of the Invention
The present invention relates to a wrench, and more particularly to a one-way drive strap wrench.
2. Description of Related Art
A strap wrench is applied for turning a cylindrical object in one direction, for example, an oil filter of a motor vehicle, such that the strap wrench is not limited by surrounding engine parts of the oil filter in the motor vehicle.
With reference to U.S. Pat. No. 6,196,090, a conventional strap wrench has a handle, a strap and a torque-transmitting shoe. The strap is mounted on the handle to form a loop and to define two opposite strap portions. The two opposite strap portions cooperate with two zones. The torque-transmitting shoe is connected with the handle between the two zones.
In use, a position of an axis of the torque-transmitting shoe is offset relative to an axis of handle to change a tension of the strap. When the axis of the torque-transmitting shoe is closer to a first point (22A in the U.S. Pat. No. 6,196,090) than to a second point (22B in the U.S. Pat. No. 6,196,090), the strap is more taut. On the other hand, when the axis of the torque-transmitting shoe is closer to the second point than to the first point, the strap is less taut. Therefore, the tension of the strap can be changed depending on the desired tightness for clamping the oil filter.
However, the torque-transmitting shoe can be offset based on the axis of the torque-transmitting shoe relative to the handle by a spring mounted around the axis of the torque-transmitting shoe and a pin that protrudes from the torque-transmitting shoe and is slidable in a slot. However, the structure between the handle and the torque-transmitting shoe is complicated. The complicated structure may require a costly and time-consuming manufacturing process.